Raluca Isopescu

Divided wall distillation column: Dynamic modeling and control

Abstract The dynamic modeling of the dividing wall distillation column is used to determine optimal startup policies that minimise the time required to reach the imposed steady state operating values in terms of product compositions and flow rates. The problem is resolved by a convenient transformation of the dynamic model in a system of differential equations, avoiding algebraic calculations generally imposed by equilibrium solving, and by using iterative, dynamic programming for the minimization of the startup time. An example referring to the separation of a ternary hydrocarbon mixture is presented. The variables that mostly influence the startup time were found to be the reflux ratio and side-stream flowrate. The optimal policies identified realise a considerable reduction of startup time, up to 70% compared to the startup operation at constant reflux ratio or constant side draw flowrate.

Romanian Honey: Characterization and Classification

Making a significant contribution to the European honey trade, Romania has been lately engaged in an exhaustive process of ensuring product conformity. Both official bodies and research groups have taken part in the efforts to establish an efficient framework for characterizing and authenticating unifloral and polyfloral honey samples produced and commercialized. Innovative contributions of different Romanian scientists to the development of simple and/or effective investigation techniques are discussed, as well as the results gained in characterizing and classifying samples according to their botanical and/ or geographical origin. Information on the honey production and commercialization in the last 25 years is also provided, as well as a sketch of the Romanian consumer profile.

Genetic algorithm optimization of fractional crystallization processes

Abstract This paper advances the optimization of fractional crystallization separation flowcharts applying genetic algorithms (GA), using as example the potassium nitrate separation. All feasible separation sequences are described using the thermodynamic state network model The optimization criterion is the minimization of the sum of flows over the entire network. The results obtained are compared with the solution found by solving the non-linear optimization problem implemented in GAMS.

Modelling and parameter estimation for transport processes in zeolite membranes

Abstract A mathematical model describing the permeation transport through a zeolite membrane has been developped. It is based on the diffusion mecanism identification from experimental data analysis. The diffusion parameters have been estimated by fitting the mathematical model to experimental data. The experiments were carried out under steady state conditions; permeate flows were measured for a large range of temperature and pressure values. The random search method proposed by Luus and Jaakola was used for the parameters estimation. Statistical analysis was performed to evaluate the confidence interval for the estimates. The results were in good agreement with experimental data.